Wideband Feeds Development G Sankar Band 250 500

Wide-band Feeds Development G. Sankar Band: 250 – 500 MHz. Pranjal’s design: Dipole within a smaller dia. of Cavity ; design formulated by Wi. PL-D software.

Measurements

Comparison of Std. Cavity backed Dipole Std. CBD Pranjal’s Cavity dia. 1. 07 * λ 0. 76*λ Cavity depth 0. 28*λ 0. 45*λ

Std. Cavity Backed Dipole

Measurements of CBD

Simulated vs. measured

Simulated Radiation parameters

Simulated cross-polar levels

Features Weight : 23. 0 kg. l ( 20. 0 + 1. 5) l l Cost : ~ Rs. 26000 / feed.

Improved BW for 327 MHz. dipole

Existing vs. Modified

Simulated Radn. parameters

Existing / Modified l Impedance BW: 292 – 469 MHz. (177 MHz. ) l Impedance BW : 289 – 524 MHz. (235 MHz. ) l Polariz. BW : 275 – 350 MHz. l Polariz. BW: 260 – 375 MHz.

Available choices … Install 250 MHz. CBD on 2 antennas & test l Scale the 250 MHz. CBD design to lower freq. band : 120 – 240 MHz. l Modified 327 Dipole – install in 10 antennas. l New designs – Conical cavity + Dipole : explore. l

Budget Estimate (2010 -2011) 10 nos. of (250 MHz. CBD) : 3. 0 lac l Antenna Range : 8. 0 lac l Hardware & Software : 1. 0 lac l CST Microwave Studio : 30 lac l l Total : 42 lac

Long-term goals l ‘LIGHT WEIGHT’ designs for 550 – 800 MHz. l New L-Band feed design with cryogenics.

Acknowledgement l Hanumanth Rao. B. l NCRA Workshop Team l FE – Lab. colleagues

… on a lighter vein … l Science is always wrong. It never solves a problem without creating ten more. : G. Bernard Shaw.